1. Field of the Invention
This invention relates generally to a high energy rechargeable battery, and more specifically to a rechargeable lithium ion battery having a carbon anode. The invention relates even more specifically to a method of preventing the electrochemical dissolution of a copper current collector in the lithium ion battery electrolyte.
2. Discussion of the Prior Art
In a lithium ion battery, the metallic lithium anode is replaced with a lithium intercalation host, which is usually a carbonaceous material. One conventional method for fabricating such an anode employs a slurry of carbonaceous material with a binder solution. Examples of the binder solution include a 5 wt. % PTFE (TEFLON) emulsion; a 2.86 wt. % polyvinylidene fluoride solution in 50:50 1-methyl-2-pyrrolidinine and tetrahydrofuran; or a 2 wt. % aqueous 2-hydroxy ethyl cellulose solution. After the slurry has been spread on an electrolytic copper foil current collector, the electrode is vacuum dried at about 120.degree. C.
A problem associated with such carbon electrodes, however, is that copper metal has been found to dissolve in the battery electrolyte and then deposit at the positive electrode, resulting in premature cell failure.
Therefore, a general need exists to provide a lithium ion battery comprising an electrolyte in which copper is not susceptible to electrochemical dissolution. An even more specific need exists to provide a method of preventing the dissolution of a copper current collector in a rechargeable lithium ion battery having a carbon anode.